Search for: prefrontal-cortex
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    Prefrontal cortex represents long-term memory of object values for months

    , Article Current Biology ; Volume 28, Issue 14 , 23 July , 2018 , Pages 2206-2217.e5 ; 09609822 (ISSN) Ghazizadeh, A ; Hong, S ; Hikosaka, O ; Sharif University of Technology
    Cell Press  2018
    As a central hub for cognitive control, prefrontal cortex (PFC) is thought to utilize memories. However, unlike working or short-term memory, the neuronal representation of long-term memory in PFC has not been systematically investigated. Using single-unit recordings in macaques, we show that PFC neurons rapidly update and maintain responses to objects based on short-term reward history. Interestingly, after repeated object-reward association, PFC neurons continue to show value-biased responses to objects even in the absence of reward. This value-biased response is retained for several months after training and is resistant to extinction and to interference from new object-reward learning... 

    Common coding of expected value and value uncertainty memories in the prefrontal cortex and basal ganglia output

    , Article Science Advances ; Volume 7, Issue 20 , 2021 ; 23752548 (ISSN) Ghazizadeh, A ; Hikosaka, O ; Sharif University of Technology
    American Association for the Advancement of Science  2021
    Recent evidence implicates both basal ganglia and ventrolateral prefrontal cortex (vlPFC) in encoding value memories. However, comparative roles of cortical and basal nodes in value memory are not well understood. Here, single-unit recordings in vlPFC and substantia nigra reticulata (SNr), within macaque monkeys, revealed a larger value signal in SNr that was nevertheless correlated with and had a comparable onset to the vlPFC value signal. The value signal was maintained for many objects (>90) many weeks after reward learning and was resistant to extinction in both regions and to repetition suppression in vlPFC. Both regions showed comparable granularity in encoding expected value and value... 

    Analysis and Comparison of the Role of SNr and vlPFC in Value Learning and Memory and Value Guided Saccade

    , M.Sc. Thesis Sharif University of Technology Kheirkhah Ravandi, Mohammad Ali (Author) ; Ghazizadeh, Ali (Supervisor)
    Learning the value of the objects in the living environment of animals has a great significance in guiding the behavior of animals. Therefore, understanding the mechanisms and structures involved in this phenomenon in the brain is one of the topics of interest in modern neuroscience. One of the most important structures known in the mammalian brain that plays an important role in learning the value of objects is the Basal ganglia. The value signal of objects has been observed in different areas of this structure. Another important area of the brain, whose role in learning the value of objects has recently been investigated, is the area of the Ventrolateral Prefrontal Cortex (vlPFC). On the... 

    Task-specific modulation of PFC activity for matching-rule governed decision-making

    , Article Brain Structure and Function ; Volume 226, Issue 2 , 2021 , Pages 443-455 ; 18632653 (ISSN) Parto Dezfouli, M ; Zarei, M ; Constantinidis, C ; Daliri, M. R ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Storing information from incoming stimuli in working memory (WM) is essential for decision-making. The prefrontal cortex (PFC) plays a key role to support this process. Previous studies have characterized different neuronal populations in the PFC for working memory judgements based on whether an originally presented stimulus matches a subsequently presented one (matching-rule decision-making). However, much remains to be understood about this mechanism at the population level of PFC neurons. Here, we hypothesized differences in processing of feature vs. spatial WM within the PFC during a matching-rule decision-making task. To test this hypothesis, the modulation of neural activity within the... 

    Rhythmic air-puff into nasal cavity modulates activity across multiple brain areas: A non-invasive brain stimulation method to reduce ventilator-induced memory impairment

    , Article Respiratory Physiology and Neurobiology ; Volume 287 , 2021 ; 15699048 (ISSN) Ghazvineh, S ; Salimi, M ; Nazari, M ; Garousi, M ; Tabasi, F ; Dehdar, K ; Salimi, A ; Jamaati, H ; Mirnajafi Zadeh, J ; Arabzadeh, E ; Raoufy, M. R ; Sharif University of Technology
    Elsevier B.V  2021
    Mechanical ventilation (MV) can result in long-term brain impairments that are resistant to treatment. The mechanisms underlying MV-induced brain function impairment remain unclear. Since nasal airflow modulates brain activity, here we evaluated whether reinstating airflow during MV could influence the memory performance of rats after recovery. Rats were allocated into two study groups: one group received rhythmic air-puff into the nasal cavity during MV and a control group that underwent ventilation without air-puff. During MV, air-puffs induced time-locked event potentials in OB, mPFC and vHPC and significantly increased the oscillatory activity at the air-puff frequency. Furthermore, in... 

    Psychogenic seizures and frontal disconnection: EEG synchronisation study

    , Article Journal of Neurology, Neurosurgery and Psychiatry ; Volume 82, Issue 5 , 2011 , Pages 505-511 ; 00223050 (ISSN) Knyazeva, M. G ; Jalili, M ; Frackowiak, R. S ; Rossetti, A. O ; Sharif University of Technology
    Objective Psychogenic non-epileptic seizures (PNES) are paroxysmal events that, in contrast to epileptic seizures, are related to psychological causes without the presence of epileptiform EEG changes. Recent models suggest a multifactorial basis for PNES. A potentially paramount, but currently poorly understood factor is the interplay between psychiatric features and a specific vulnerability of the brain leading to a clinical picture that resembles epilepsy. Hypothesising that functional cerebral network abnormalities may predispose to the clinical phenotype, the authors undertook a characterisation of the functional connectivity in PNES patients. Methods The authors analysed the whole-head... 

    Allergic rhinitis impairs working memory in association with drop of hippocampal – Prefrontal coupling

    , Article Brain Research ; Volume 1758 , 2021 ; 00068993 (ISSN) Salimi, M ; Ghazvineh, S ; Nazari, M ; Dehdar, K ; Garousi, M ; Zare, M ; Tabasi, F ; Jamaati, H ; Salimi, A ; Barkley, V ; Mirnajafi Zadeh, J ; Raoufy, M. R ; Sharif University of Technology
    Elsevier B.V  2021
    Allergic rhinitis (AR) is a chronic inflammatory disease frequently associated with a deficit in learning and memory. Working memory is an important system for decision making and guidance, which depends on interactions between the ventral hippocampus (vHipp) and the prelimbic prefrontal cortex (plPFC). It is still unclear whether AR influences the activity and coupling of these brain areas, which consequently may impair working memory. The current study aimed to examine alterations of the vHipp-plPFC circuit in a rat model of AR. Our results show decreased working memory performance in AR animals, accompanied by a reduction of theta and gamma oscillations in plPFC. Also, AR reduces... 

    Transcranial DC stimulation modifies functional connectivity of large-scale brain networks in abstinent methamphetamine users

    , Article Brain and Behavior ; Volume 8, Issue 3 , 2018 ; 21623279 (ISSN) Shahbabaie, A ; Ebrahimpoor, M ; Hariri, A ; Nitsche, M. A ; Hatami, J ; Fatemizadeh, E ; Oghabian, M. A ; Ekhtiari, H ; Sharif University of Technology
    John Wiley and Sons Ltd  2018
    Background: Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation tool suited to alter cortical excitability and activity via the application of weak direct electrical currents. An increasing number of studies in the addiction literature suggests that tDCS modulates subjective self-reported craving through stimulation of dorsolateral prefrontal cortex (DLPFC). The major goal of this study was to explore effects of bilateral DLPFC stimulation on resting state networks (RSNs) in association with drug craving modulation. We targeted three large-scale RSNs; the default mode network (DMN), the executive control network (ECN), and the salience network (SN). Methods:...